Mickey Delp dot com


My x0x-heart

I bought the x0x-heart circuit board from Open Music Labs The x0x-heart is a clone of the TB-303 voice. It is just the synth voice, without a sequencer. That suits me just fine because I build my own sequencers and I am always looking for stuff to sequence. The x0x-heart is sold as a circuit board fully populated with surface mount parts. The only (ha, only) things missing are the pots, switches, jacks and an enclosure. Bottom line: I love it! It sounds just like a 303, and for $79 bucks, a DIYer can’t go wrong.

All of the information you need to assemble the x0x-heart is in the x0x-heart Wiki, so I won’t repeat all of it here. However, Open Music Labs included a lot of options in their design, and I will talk about how I implemented those options and how I would do it differently next time.


I used a gray case to sort of match the TB-303’s silver case. That enclosure also comes in black or tan. The printing on the control panel was done with my usual technique. I ink jet print the text and graphics on a sheet of vinyl sticker stock, cut out the holes with a Silhouette Cameo digital cutter, spray it with Krylon Preserve-It, then stick it on. For this design, I used a background image of brushed aluminum, which matches the gray case well and adds a subtle classiness. The typeface was chosen to match the Open Music Labs logo. To give it a splash of color, I chose red knobs and red switch caps. I am very pleased with the overall look of it.

Click here to read all about the x0x-heart

The Golden Age of the Home Computer

On September 11, 2013, I did a presentation at Nerd Nite Austin on The Golden Age of the Home Computer.  It features many machines from my personal collection.  I didn't want to take my whole collection with me, so I tried to think of a sensible way to limit it.  I came up with the a 30th anniversary concept, and so only took those machines which would have been available to purchase in 1983.  That turned out to be way more than I expected - 19 machines, which is over half of my collection.  As I did more research for the presentation, I found that 1983 was a very significant year in the history of home computers.  I hope you enjoy the video!

"The Golden Age of the Home Computer," by Mickey Delp from Nerd Nite - Austin on Vimeo.

Panoramical Controller

Panoramical Arcade Cabinet

I built a custom arcade controller for an incredible new game called Panoramical. It is not a game in the traditional sense, in that there is no objective. It is an immersive visual and auditory landscape where you are in control of the geography and music. Just as Panoramical is not your typical game, the controller is not your typical joystick. The game is controlled by a set of 18 knobs and sliders that each has an effect on the landscape. Panoramical is a collaborative project by Fernando Ramallo and David Kanaga. Their development schetchbook has some great pictures and videos of the game.

The custom controller was built to show off Panoramical in an arcade cabinet at Fantastic Arcade 2013. Fantastic Arcade showcases new indie games, and is part of the annual Fantastic Fest film festival in Austin, Texas.

Click here for more pictures and to read all about the Panoramical Controller


After I built the NeinOhNein hand clap pedal, I was inspired to create my own hand clap circuit – the Thunderclap. When I designed the LDB-1 Drum Machine, I included a simple hand clap. The sound is just filtered white noise, as in most analog drum machines. What makes the classic TR-808/909 hand clap sound so distinctive is the four part volume envelope. That is how they simulated multiple people clapping at not quite exactly the same moment. The Thunderclap faithfully reproduces the classic waveform, plus adds tweakability.


Read more about the Thunderclap

Hand Clap Pedal

This is my first attempt at painting a custom pedal. Up until now, I have always used inkjet printed vinyl stickers on my custom pedals.

NeinOhNein Clap Pedal

The pedal is built around the hexinverter.net NeinOhNein Clap circuit board, a clone of the clap sound from the TR-909. Hex Inverter has some great products including a whole series of 909 clone circuit boards.

The board is intended to be used in a modular synthesizer which supplies +/-12 or +/-15 volts. I wanted to use a standard 9V pedal power supply, so I did some testing. The circuit does not work well with +/-4.5 volts, so a virtual ground circuit was out. By not working well, I mean it had a hiss. I have noticed that with other circuits when trying to run them with very low voltages. So, I used a TC1044S charge pump chip to provide the -9V. I added an LED illuminated push-on/push-off power switch, a big button to trigger the clap sound, and a trigger input jack so the sound can be triggered by a drum machine or sequencer or whatever. I wired a diode in series from the jack and from the button to keep the voltage from either source from flowing into the other.

Building the electronics was relatively straightforward. The real project for me was making the enclosure look good!

Read more: Hand Clap Pedal

The Effeutron Autonomous Noise Music Machine

The Effeutron is a device I created specifically for the Wall Only Fest.  It is an autonomous noise wall music generating machine.  It has eight independent oscillators each with its own LFO and variable period gate, using four CD40106 chips.  The oscillators themselves are gated in sequence by the CD4040 divider chip.  A CD4049 chip provides a clock for the divider as well as a tube-sound fuzz effect.  It runs through all 255 combinations of the oscillators, then stops.

It really doesn't have to run hands-off. There are 50 parameters that can be adjusted while it is playing. The amount of fuzz and the speed of the clock can be adjusted. Each of the oscillator blocks has six trimmer potentiometers to modify the sound. There are a lot of sonic possibilities here!

It was a fun project to build, but not being a noise musician, I probably won't use it again. If you are interested in owning the one-and-only Effeutron, feel free to contact me and make an offer.

Update: The Effeutron is sold. Congratulations to Nicholas in Australia. Have fun with it!


The Effeutron


Read more: The Effeutron Autonomous Noise Music Machine

Anatomy of a Drum Machine

This is the story of the design and development of the Delptronics LDB-1 Analog Drum Machine with a focus on the technical details.

I had been studying analog drum circuits for about a year, including both classic drum machines and more modern drum circuits and modules. In January of 2012, having just finished several projects, I felt it was time to dive into building some drum circuits. My goal was to build a small, low cost drum machine, and I knew that the first step was to get the sounds right. I breadboarded every drum circuit I could find and compared the results with samples from the classic drum machines, particularly the venerable Roland TR-808. I worked on it full time for two weeks. By the end of that time, I had the circuits refined and tuned and sounding just the way I wanted them.

The one sound I could not get quite right was a rim-shot. The closest I could get was a woodblock. I figured it was time to build a prototype and I would get back to the rim-shot sound later. To my surprise, I got a lot of compliments on the woodblock sound, so I kept it as is.

I then went through the process of choosing a microcontroller to be the brains of the drum machine. That process is described in more detail below. I worked out the basic code for a microcontroller triggering the drums and built the prototype. Having worked out the bugs, I designed a printed circuit board and built several devices.

The most time-consuming step in the development of the LDB-1 was to program all of the features. I went through many iterations of the code to get every feature of a classic drum machine into the LDB-1 with an easy to use interface. A three month long beta test cycle really paid off.

When development was complete, there was still a ton of work needed before it could go to market, tasks like writing the user manual, sourcing the components, assembly, the design and production of the enclosure, and so on.


Original Prototype Final Production Model
LDB-1 Drum Machine Prototype LDB-1 Drum Machine


The Circuits

The rest of this article is a description of the LDB-1 circuits. The information presented below should provide you with all of the information that you need to understand and even modify the LDB-1. If you have specific questions not answered by this article, please feel free to contact me. As you read the article, follow along with the LDB-1 Schematic .

Read more: Anatomy of a Drum Machine

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